Slightly related to this question Esther's Hebrew name was Hadassah. I understand the use of that name in the Megillah. However in our liturgy including the Al haNissim prayer and other songs and piyutim we continue to refer to her as Esther instead of Hadassah. We do not do this for other Jews who were given or assumed foreign names (ex. Shadrach, Meshach, and Abednego). I would like to understand why we do not use Esther's Hebrew name in our prayers and piyutim.
Main points and answers in Bold.
There are many aspects that need to be discussed in order to properly answer this question, but this will only really be a question according to the (minor) minority opinion that your question is based on, that Esther is a foreign, name, whereas Hadassah is a Hebrew name. This will be shown below.
The answer according to that minority opinion is that @Mevaqesh is absolutely right - we likely developed this from the fact that (almost) all times that she is named in scripture, she is referred to as Esther. This is compounded by the fact that we read Megillas Esther (note the name of the book!) yearly, and all of us are present to hear it, so we know her by that name. This fact makes it different than all of the other cases mentioned in the question. (How many times have you heard of Shadrach?)
Then we get to the actual understanding of the name Esther vs. the name Hadassah. Here is a short summary of some of the commentaries who deal with that in Megillas Esther, and the Gemara, and how their approaches will answer this question by disagreeing with the premise outlined above, or providing another answer:
- Chazal (Megillah 13a) have a Machlokes which was her real name:
רבי מאיר אומר: אסתר שמה, ולמה נקרא שמה הדסה - על שם הצדיקים שנקראו הדסים, וכן הוא אומר (זכריה, א', ח') "והוא עומד בין ההדסים". רבי יהודה אומר: הדסה שמה, ולמה נקראת שמה אסתר - על שם שהייתה מסתרת דבריה, שנאמר "אין אסתר מגדת את עמה וגו'". רבי נחמיה אומר: הדסה שמה, ולמה נקראת אסתר - שהיו אומות העולם קורין אותה על שום אסתהר. בן עזאי אומר אסתר לא ארוכה ולא קצרה היתה אלא בינונית כהדסה ר' יהושע בן קרחה אמר אסתר ירקרוקת היתה וחוט של חסד משוך עליה
Here is an outline of the 3 major opinions, as relevant to our discussion:
- Rabbi Meir, Ben Azzai, Rabbi Yehoshua Ben Karchah - Her real name was Esther, and she is referred to as Hadassah for some Midrashic reason.
- Rabbi Yehudah - Her real name was Hadassah, but we refer to her as Esther because she hid her "nationality" and "birth".
- Rabbi Nechemiah - Her real name was Hadassah, and the non-Jews called her Esther.
According to opinion 1 (what I would consider the Gemara's majority opinion), her only real name was Esther, and she was called Hadassah, so we refer to her as Esther because that was her real name. According to opinion 2, we call her Esther in the Megillah because she hid her nationality from Achashveirosh, and therefore, we would continue calling her Esther from then on, despite it not being her real name. Your question applies only to number 3. I will bring other opinions to show that we do not seem to accept the view that Esther was simply her non-Jewish name. Note that there are other versions of the found in various Midrashim, with a few different reasons given, but the basics are the same. (This is where the idea of "Hester Panim" may fit in, similar to opinion 2.)
Here are some other opinions that are not based on the Gemara (many Rishonim and Acharonim choose one of the opinions mentioned above and support it, see above for links to all of the commentaries):
- Ri Kara says that the word Hadassah is simply the word they used in Shushan to describe a young girl, and that her name was actually Esther
- Ibn Ezra mentions multiple opinions (some in derash), but understands according to peshat that Esther is indeed a translation of Hadassah into Persian, according to the second opinion, the question must be addressed by our original answer
- Rashbam seems to suggest that Hadassah was some sort of nickname for that Esther (how she was known), and that her name was actually Esther
Edit: Shout out to @DoubleAA who essentially wrote this answer in the shortest way possible. Shout out also to Ezra, who points out that she was much more known in her role as Queen Esther, even if her Hebrew name was Hadassah.